Pour info,même si ça arrive tardivement
et que ce serait toujours mieux dans la section règles, je fais un très rapide résumé à la fin en français :
A common question is how do some of the tricky Tau attachment effects interact. These include:
Commander Shadowsun: "After this warlord commits to a planet, put a {T} attachment with printed cost 2 or lower or "Shadowsun's Stealth Cadre" from your hand or discard pile into play ..."
Shadowsun's Stealth Cadre: This card may enter play as an attachment with the text, "..."
Gun Drones: You may deploy this card as a Drone attachment, with the text "..."
Ambush Platform:Action: Exhaust this support to deploy an attachment from your hand.
Interrupt: When you deploy an attachment, reduce its cost by 1.
Firstly, Deploy (where you must pay) and Put Into Play (where you don't pay) are both subsets of "Enter Play". If an ability checks whether something has "entered play", it doesn't matter if it's been deployed or put into play, both satisfy the "entered play" criteria.
Shadowsun allows you to "put into play" an attachment or Cadre (for free). This includes all physical attachments obviously, but also any units that have an effect that allows them to be "put into play" or "enter play" as an attachment. This includes Cadre - which is named in the effect purely to make it obvious that this is legal, but it needn't have been because its effect allows it to enter play as an attachment (ie allowing it to be either "deployed" or "put into play" as an attachment).
(A technical aside: note that there is no use of the word "target" in Shadowsun's effect. If there had been, then the chosen attachment would have to be in your hand/discard pile when the effect was initiated. This would have then excluded Cadre, which only becomes an attachment when it enters play. One of the rules is that you're not allowed to initiate an effect unless it can change the game state - Shadowsun's effect can be initiated because Cadre's effect allows Shadowsun's effect to successfully resolve ... an attachment does in fact enter play, even though it wasn't an attachment in your hand when you initiated the effect.)
Shadowsun cannot however put Gun Drones into play. Gun Drones can only enter play as an attachment by being "deployed" (ie being paid for). Because "deploy" and "put into play" are mutually exclusive, its effect does not allow it to be put into play as an attachment, which is what Shadowsun is trying to do. Cadre on the other hand specifies it can "enter play" as an attachment, which means it can enter play by either method.
Ambush Platform allows you to "deploy" an attachment. Both Gun Drones and Cadre satisfy that criteria (ie both are allowed to be "deployed" as an attachment), so both may enter play via Ambush Platform's effect. When you deploy either, Ambush Platform's interrupt (the cost reduction) will work on both - an attachment being deployed has been initiated, therefore the cards are now attachments, and it's legal to interrupt it and reduce its cost.
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Lastly, remember that Cadre and Gun Drone are not attachments when they're in your hand or discard pile. They're still units. They only become attachments at the point the process initiates for them to enter play as such. Therefore for:
Earth Caste Technician: "After this unit enters play, search the top 6 cards of your deck for an attachment or Drone card. ..."
ECT does not find Cadre. It does find Gun Drones however - not because it's an attachment, but because it has the Drone trait.
Source.Pour faire court et en français :
1- Shadowsun ne peut mettre en jeu un Gun Drones mais il peut aussi mettre en jeu n'importe qu'elle carte qui comme Shadowsun's Stealth Cadre
peut devenir un attachement quand elle entre en jeu , ce qui n'est pas le cas des Gun Drones, qui sont
déployé comme des attachements. Une carte qui serait mise en jeu comme un attachement fonctionnerait aussi.
2- Ambush Platform, permet de mettre en jeu un Gun Drones et un Shadowsun's Stealth Cadre, de la même manière elle réduit le coût de chacun.
3- Bonus : Earth Caste Technician ne permet pas d'aller chercher des Shadowsun's Stealth Cadre